Direct Temporal Synthesis of Terahertz Light Fields Enabling Novel Computational Imaging

Project Information

DIRECTS

Grant agreement ID: 101019972

DOI

10.3030/101019972

EC signature date 21 July 2021

Start date 1 October 2021

End date 30 September 2026

Funded under

• EXCELLENT SCIENCE - European Research Council (ERC)

Total cost

€ 2 477 947,00

EU contribution

€ 2 477 947,00

Coordinated by

BERGISCHE UNIVERSITAET WUPPERTAL
Germany

Periodic Reporting for period 3 - DIRECTS (Direct Temporal Synthesis of Terahertz Light Fields Enabling Novel Computational Imaging)

Reporting period: 2024-10-01 to 2026-03-31

Summary of the context and overall objectives of the project

The DIRECTS project ("Direct Temporal Synthesis of Terahertz Light Fields Enabling Novel Computational Imaging") focuses on researching a completely new approach to better exploit the potential of terahertz radiation in the creation of 3D images. Terahertz radiation is so interesting because, among other things, it makes it possible to see inside opaque objects and is harmless to humans - unlike X-rays. "Terahertz waves have a unique interaction with matter and pass through materials such as cardboard, plastic, ceramics, paper, fabric, etc.," says project initiator Prof. Pfeiffer. In theory, this opens up numerous interesting applications, for example in industrial quality control or security screening, such as screening an envelope or luggage at the airport. But there are catches: the terahertz radiation that occurs in the natural environment is very weak, and in addition, the manufacturing process of compact and powerful transmitter and receiver devices for the terahertz frequency range is still in its infancy. It is still unthinkable to make clearly visible 3D images through opaque materials.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

The actions implemented for this 30-month reporting period can be subdivided into the four project objectives and the project management.
Initial actions in Objective 1 (Fundamental framework) were related to "THz light-field theory and simulations". This included final EM simulations of light-field macro-pixels in special EM solvers like Zemax and HFSS. Results were obtained on ray-propagation, imperfections due to optical aberrations, and on-chip antenna patterns.
Design trade-offs were the primary focus on in Objective 2 (System optimization). Optimization was done in terms of resolution limits, implementation loss, and number of pixels have been fixed. Results were obtained on macro-pixel lens geometries by the use of hyper-hemispherical Si lens configurations now based on 3D machined ceramics.
Circuit design activities made substantial progress in Objective 3 (System implementation) with the primary focus on establishing a mixed-signal RF/THz design flow in IC design tools like ADS, Cadence and open design tools. Initial source and camera pixel designs were implemented for "Temporal THz Light-Field Generators" and "THz Light-Field Cameras" (patent filed). One implementation of a fast parallel video controllers in "THz Light-Field System Integration" has been selected.
Actions in Objective 4 (Algorithms) included initial studies on the recursive synthesis of THz light-fields for the purpose of performing measurements and publications.
Finally, the actions in the Project Management were mostly related to recruitment of qualified personnel, the coordination of the WP tasks, and the planning of publications and dissemination activities such an invited talk at the European Machine Vision Forum (EMVF), an invited talk at the Advances in Analog Circuit Design workshop (AACD), preparation of book chapters, and a Inspect-Europe journal article for machine vision and optical measuring technology in industrial applications.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

Light-field techniques are unavailable for THz frequencies so far. This problem also originates from the lack of a cross-disciplinary approach – there is no complete THz light-field theory that the circuit and system designers can work with, and there are no THz systems that adopt well to the light-fields for their formalization and validation. The main objective of DIRECTS is to enable THz light-fields with a comprehensive research into its multiple facets, for demonstrating video-rate, 3-D see-through imaging at THz, conforming to a formalized THz light-field theory. It is also planned to research on a system design road-map that will aid other researchers to design and improve their own THz light-field systems. Part of the research is also dedicated to development of efficient 3-D see-through algorithms that can also utilize the temporal diversity in THz light-fields.

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